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  • Name: SA387 Gr11 / Gr22 / Gr91
  • Code: 387
  • Time: 2015-02-01
  • Views : 410
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SA 387 Grade Plate

The chrome moly plates are generally available in two specifications ASME SA387 and ASTM A387. The chemical and mechanical properties for ASME and ASTM plates are same and are described as "Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum" 

Application

  • These plates are commonly used in the high temperature conditions for welded boilers and pressure vessels

Plates are available under these specifications in several grades each having different nominal Chromium (Cr) and Molybdenum (Mo) contents as follows :
Grade Nominal Cr Content (%) Nominal Mo Content (%)
2 0.5 0.5
12 1 0.5
11 1.25 0.5
22, 22L 2.25 1
21, 21L 3 1
5 5 0.5
9, 91 9 1

Each grade except Grades 21L, 22L, and 91 is available in two classes of tensile strength described as Class 1 and Class 2. The most regularly specified grades and hence those that are most readily available from stock are Grades 12, 11, 22, 5, and 9 and in most case stock plates will be produced to the tensile requirements of Class 2. 

The following tables give information on the chemical and mechanical properties of all of the grades :

Chemical Requirements

(cast analysis, % by mass, maximum permitted unless indicated otherwise)
  Gr. 2 Gr. 12 Gr. 11 Gr. 22 Gr. 22L Gr. 21 Gr. 21L Gr. 5  Gr. 9 Gr. 91*
C 0.05-0.21 0.05-0.17 0.05-0.17 0.05-0.15 0.1 0.05-0.15  0.10   0.15  0.15 0.08-0.12 
Mn 0.55-0.80 0.40-0.65  0.40-0.65 0.30-0.60  0.30-0.60  0.30-0.60  0.30-0.60  0.30-0.60  0.30-0.60  0.30-0.60 
P 0.025 0.025  0.025 0.025 0.025  0.025  0.025  0.025  0.025  0.020 
S 0.025 0.025  0.025  0.025  0.025  0.025  0.025  0.025  0.025  0.010 
Si 0.15-0.40 0.15-0.40  0.50-0.80 0.5 0.50  0.5 0.5 0.5 1.00  0.20-0.50 
Cr 0.50-0.80 0.80-1.15  1.00-1.50  2.00-2.50 2.00-2.50 2.75-3.25 2.75-3.25 4.00-6.00 8.00-10.00  8.00-9.50
Mo 0.45-0.60 0.45-0.60  0.45-0.65 0.90-1.10  0.90-1.10 0.90-1.10 0.90-1.10 0.45-0.65 0.90-1.10 0.85-1.05 
V  -  -  - -  -  -  - - 0.04  0.18-0.25


Tensile Requirements


Class 1 Plates锟�
Grade Tensile (MPa) Yield (MPa) Elong. (50mm) Reduc'n of Area*
2, 12 380 - 550 230 min 22% min -
11 415 - 585 240 min 22% min -
22, 21, 5, 9 415 - 585 205 min 18% min 40% min
21L, 22L  415 - 585 205 min 18% min 40% min

Class 2 Plates
Grade Tensile (MPa) Yield (MPa) Elong. (50 mm) Reduc'n of Area*
 2 485 - 620 310 min 22% min -
11 515 - 690 310 min 22% min  -
12 450 - 585 275 min 22% min -
22, 21, 5, 9 515 - 690 310 min 18% min 40% min
91 585 - 760 415 min 18% min -